Position-independent mercury relay



p 15, 1970 I u. RAUTERBERG 3,529,268

POS ITION- INDEPENDENT MERCURY RELAY Filed Nov. 29, 1968 r BY W V I ATTYS.

United States Patent Office US. Cl. 335-56 14 Claims ABSTRACT OF THE DISCLOSURE A position-independent mercury relay having two pairs of magnetically and electrically conductive contacts with one end portion of each contact forming a portion of an interior wall surface of a hermetically switching sealed space. The hermetically sealed space contains a floating armature surrounded by a mist of mercury droplets. At least one pair of the contacts may provide oppositely poled magnets establishing a magnetic flux within the space to normally maintain the floating armature in a rest position in bridging relationship with that pair of contacts. An energizing field is provided to selectively overcome the magnetic flux within the space and switch or move the armature into bridging relationship with the other pair of contacts. The armature is sized to sweep the entire available volume of the switching space to collect the mercury droplets between the contacts bridged and the armature for forming a fluid connection.

BACKGROUND OF THE INVENTION Field of the invention This invention generally relates to a mercury relay, and more particularly refers to a position-independent mer cury relay having a hermetically sealed switching space containing a floating armature and a mist of mercury droplets.

Description of the prior art The use of a liquid connection instead of a direct metalto-metal contact for achieving a bounce free connection having a low electric transition resistance has been proposed heretofore, and, as a rule, mercury has been utilized as a switching liquid. The use of mercury as a switching liquid has provided switching contacts capable of transmitting relatively high electric currents without causing either a welding of the contacts or an alteration of the contact surfaces by metal transportation between the contacts.

Although liquid mercury relays have provided several advantages, such relays which include a mercury reser voir have enjoyed a limited usage since the mercury reservoir necessitates installing the relay in a certain position. Even when the mercury is provided only for wetting of the contacts, a mercury reservoir has normally been provided for gravitationally collecting the mercury to provide a source of mercury for spraying onto the contacts to maintain the wetting thereof.

Also, in electromagnetic relays heretofore proposed, the armature has normally been mechanically supported by a bearing pin or by a correspondingly designed bearing spring. The mechanical supporting or positioning means for the armature, however, may cause a bearing friction, which in many cases, and particularly in miniaturized relays having a high sensitivity of response, is not negligible.

SUMMARY OF THE INVENTION The present invention provides an electromagnetic relay having contact-making parts wetted with mercury and 3,529,268 Patented Sept. 15, 1970 also having a configuration eliminating any requirement of a mercury reservoir. An electromagnetic relay constructed in accordance with the present generally includes a member forming a hermetically sealed switching space and constructed of a material which is neither electrically conductive nor magnetizable. The switching space contains a mist of mercury droplets and a floating armature. Two pairs of contact elements are provided with an end portion of each contact element embedded into the member defining the switching space such that each contact element provides a contact surface formed as a portion of an interior wall surface of the switching space. The floating armature provides an electrical bridging member between pairs of the rigid contact elements and is movable within the switching space between bridging relationship with opposed pairs of the contact elements to execute the switching operation.

In accordance with the present invention, the floating armature is sized relative to the switching space to sweep the entire available volume of the switching space as the armature moves from a position bridging one pair of contact surfaces into a position bridging another pair of contact surfaces. Thus, when the floating armature moves or switches between the pairs of contact surfaces all of the mercury droplets scattered within the switching space are collected between opposed end portions of the floating armature and the contact surfaces operatively engaged by the armature.

With this construction, a mercury reservoir for gravitationally collecting the mercury utilized to wet the connection is eliminated, thereby to provide a relay having mercury-wetted contacts and not requiring any particular position or orientation for proper operation.

Also, in accordance with the principles of the present invention, one or more rests positions may be provided for the floating armature by premagnetizing one or both pairs of contact elements. To accomplish the desirable objective, one form of the invention may include constructing the armature of a sheet formed member having a V- shaped configuration in transverse cross-section and arranging the contact elements so that two contact elements form coplanar surfaces on an interior of the switching space and the remaining two elements form a canted surface converging inwardly of the switching space toward the coplanar surfaces. The canted surfaces are preferably formed at the same angles as winged sections of the V-shaped armature, and with this configuration, the aperture moves with a semi-rotational action to alternatively form an electrical bridge between pairs of contact elements including one canted surface and a diametrically opposed coplanar surface.

The contact elements also form magnetic conductors to establish a magnetic flux within the switching space, and the magnetizing forces are provided by a pair of permanent magnets of identical polarization, each, of which is disposed between and electrically insulated from a pair of contact elements of dilferent electrical circuits, thereby to establish a magnetic flux within the switching space for maintaining the V-shaped aperture in engagement with either pair of electrical contacts forming one electrical circuit until an external force is applied to rotate the aperture into engagement with a pair of contact elements of another electrical circuit.

Another form of the invention may include an armature which moves in a linear manner to sweep the switching space as the armature is switched from engagement with one pair of electric contact elements of a first electrical circuit to engagement with the other pair of contact elements of a second electrical circuit. In this form of the invention, the armature desirably comprises a member having a rotationally symmetrical configuration, for

example-a disk or a plate member. Also, in this embodiment of the present invention, the contact elements are arranged with a pair of contact elements of one circuit forming substantially aligned surfaces in the interior of the switching space and with the other pair of contact elements forming mirror-imaged surfaces on an opposite side of the interior of the switching space. The pair of permanent magnets providing the magnetic flux are disposed between two pairs of contact elements of different electrical circuits and are oppositely polarized.

It is contemplated by the present invention that the external energizing force be provided by an electrically conductive winding encircling the element forming the switching space in a manner such that passing an electric current through the winding will create a magnetic flux within the switching space to switch the armature between the pairs of electric contact surfaces.

Therefore, the present invention provides a relay having mercury-wetted contacts in a configuration permitting miniaturization due to the elimination of a mercury reservoir and also the elimination of a mechanical supporting means or spring-like biasing means. Also, the relay constructed in accordance with the present invention substantially eliminates hazardous consequences resulting from the spillage of mercury in the event the relay is destroyed, since the relay does not require a reservoir of mercury.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawing, forming a part of this specification and in which like reference characters are employed to designate like parts throughout the same:

FIG. 1 is a transverse sectional view with certain parts shown in elevation for clarity schematically illustrating a position-independent relay constructed in accordance with one embodiment of the present invention; and

FIG. 2 is a view similar to FIG. 1 schematically illustrating another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing, and first particularly referring to FIG. 1, there is illustrated a position-independent relay constructed in accordance with the principles of one embodiment of the present invention and indicated generally at 1. The relay 1 generally includes two pair of contact elements 2a, 2b and 3a, 3b a centrally disposed member 4 defining a switching space 5 containing a mist of mercury droplets, a floating armature 6, an electrically conductive winding 7 encircling the central member 4 and the contact elements, and a pair of end caps 8, 8.

In accordance with the principles of the present invention, the central element 4 is formed of a material which is neither electrically conductive nor magnetizable, for exampleglass. Also, since mercury will not wet glass, glass is a preferred material when mercury is utilized as a wetting agent for the contacts. Each contact element 2a, 2b, 3a or 312 comprises a bar member having one end portion thereof embedded in the central member 4 and having an opposed end portion thereof passing through properly configured apertures, as at 9, formed in either end cap 8, 8. The outermost end portion, as at 11, of each contact element 2a, 2b, 3a and 311 extends beyond the pair of end caps 8, 8 to provide means for connecting the relay 1 into electric circuits. The end caps 8, 8 are formed of an insulating material to electrically insulate adjacent contact elements.

In the form of the invention illustrated in FIG. 1, the contact elements 2a, 2b, 3a and 3b are arranged in two aligned pairs of parallel elements, with elements 2a and 2b grouped into one pair and elements 3a and 3b grouped into another pair. The innermost end portions of the contact elements 2a, 2b, 3a and 3b, which are embedded into the central member 4 define portions of an interior wall surface of the switching space 5, with contact elements 2b and 3b forming coplanar surfaces 12 and 13, respectively. The innermost end portions 14 and 16, respectively of the contact elements 2a and 3a, are bent toward the contact elements 2b and 3b to form a pair of canted wall surfaces 17 and 18, respectively, of the switch ing space 5. I The armature 6 comprises a sheet-formed member having a substantially V-shaped configuration in transverse cross section with the included angle between the portions forming the V equal to the included angle formed between the bent end portions 17 and 18 of the contact elements 2:: and 3a. With this configuration, the armature 6 is movable in a rotational manner between simultaneous engagement with contact elements 3a and 2b and simultaneous engagement with contact elements 2a and 3b.

Also, in accordance with the principles of the present invention, the armature 6 is sized relative to the switching space 5 to completely sweep the entire available volume of the switching space as the armature moves between engagement with the diagonally opposed pairs of contact elements 2a, 3b and 2b, 3a. The central member 4 is formed in a manner to hermetically seal the switching space 5, and a mist of mercury droplets is contained within the sealed cavity or space 5. Thus, as the armature 6 rotates between alternative engagement with the diagonally opposed pairs of contact elements the switching space 5 is swept and the mercury droplets disposed on opposed sides of the armature are squeezed between the armature end portions and the end portions of the contact elements engaged, thereby to form a fluid connection between the armature and the contact elements. In this manner, the present invention provides a relay having mercury wetted contacts without requiring a reservoir containing a source of mercury for wetting the contacts.

Furthemore, in accordance with the principles of the present invention, a pair of identically polarized permanent magnets 19 and 21 are provided with one magnet disposed between each parallel pair of contact members 2a, 2b and 3a, 3b. Thus, with the armature 6 bridging either of the diagonally opposed pairs of contact elements 2a, 3b and 2b, 3a a conduction is established between different poles of the permanent magnets 19 and 21, thereby to provide two stable rest positions with the adhesive force being determined by the active field strength of the permanent magnets. Although the embodiment illustrated in FIG. 1 provides two stable rest positions, one stable may be provided by magnetizing only one pair of diametrically opposed contact elements with opposite polarization.

The encircling winding 7 is electrically connected to an energizing circuit utilized for switching the armature between the two pairs of dagonally opposed contact surfaces provided b the contact elements 2a, 2b, 3a, and 3b. The armature 6 of the relay 1 is switched by passing a current pulse through the winding 7 to create an electrically induced flux superimposed upon the permanent flux in such a manner that the resulting flux in the switching space 5 is greater than the flux provided by the permanent magnet. Depending upon the direction of flow of the electric current pulse through the winding 7, the armature 6 will switch either from the diagonally opposed pair of contact elements 2a, 3b or 3a, 2b to the other pair of diagonally opposed contacts. When the current pulse through the exciter winding ceases, the permanent flux provided by the permanent magnets 19 and 21 maintains the armature 6 in the switched position.

As illustrated in FIG. 2, an alternate form of the relay, indicated generally at 1, includes an armature 6' which moves in a linear manner within the switching space 5' instead of the rotational manner described for the armature 5 of the first embodiment as illustrated in FIG. 1. Elements of the alternate embodiment as illustrated in FIG. 2 which are similar to the elements of the first embodiment as illustrated in FIG. 1 are designated with like reference characters to which a prime has been added.

In accordance with the principles of the alternate embodiment of the present invention, the armature 6 comprises a substantially disk shaped member with opposite side surfaces thereof having a substantially spherical configuration, thereby to provide a member having a rotationally symmetrical configuration. The switching space 5' is sized and configured relative to the armature 6' such that the armature completely sweeps the entire available area of the switching space as the armature linearly moves between aligned pairs of contact surfaces provided, respectively, by the pairs of contact elements 2a, 2b and 3a, 3b. In a manner similar to that of the first embodiment, the armature 6 provides both an electrical bridging member for electrically connecting a pair of contacts to complete an electrical circuit and also provides a magnetically conducting member.

Since pairs of aligned contact elements, either 2a and 3a or 2b and 3b provide two mirror-imaged pairs of substantially coplanar contact surfaces for alternatively completing two different electrical circuits, instead of diagonallly opposed pairs of contact surfaces as described for the first embodiment, the permanent magnets 19' and 21' are arranged to be oppositely polarized. Also, the armature 6' may be formed with a centrally disposed aperture 22 to provide a pressure compensating means and also to reduce the armature mass.

Although two forms of the present invention have been described herein, the principles of the present invention are applicable to differently configured armatures which move in a manner to sweep the entire available volume of the switching space for squeezing the droplets of mercury contained within the switching space into the area between the armature and operatively engaged contact surfaces formed as a portion of an interior wall surface of the switching space. Also, although liquid mercury is a preferred fluid for utilization in the present invention, other electrically conductive liquds may be utilized in place of mercury.

Although minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted thereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention:

1. A position-independent relay comprising:

means forming a sealed switching space;

means providing two pairs of contact elements forming two pairs of spaced apart, electrically conductive contact surfaces on portions of interior wall surfaces of said switching space, each said contact element being electrically connectable exteriorly of said means forming said sealed switching space;

means forming an electrically conductive armature disposed within said switching space for selective movement between said pairs of contact surfaces to provide an electrically conductive bridge between said contact surfaces of either of said pairs, said armature being sized and configured relative to said switching space to sweep an entire volume of said switching space in moving from bridging relationship with either of said pairs of contact surfaces into bridging relationship with said other pair of contact surfaces;

a supply of electrically conductive fluid contained within said switching space in sufficient quantity to only wet said armature and said contact surfaces; and

selectively operative means for moving said armature from bridging relationship with either of said pairs of contact surfaces into bridging relationship with said other pair of contact surfaces,

whereby, scattered droplets of said electrically conductive fluid are collected and forced between said armature and said one pair of contact surfaces being electrically bridged by said armature as the latter sweeps said switching space in moving between said pairs of contact surfaces to form a fluid connection.

2. A relay as defined in claim 1 and further characterized by.

two said contact surfaces being formed substantially coplanar, and other two said contact surfaces being canted inwardly of the switching space in a V-shaped configuration and projecting toward said coplanar contact surfaces;

each said pair of contact surfaces including diagonally opposite contact surfaces; and

said armature means including a sheet-form member having a V-shaped configuration in transverse cross section and movable in a rotational manner in switching between said pairs of contact surfaces.

3. A relay as defined in claim 2 and further characterized by:

a pair of identically polarized permanent magnets disposed outwardly of said means forming said switching space,

each said permanent magnet extending between different pairs of contact elements including one said element forming one said coated surface and one said element forming one said coplanar surface,

whereby, said pair of permanent magnets premagnetize said contact surfaces with diagonally opposed contact surfaces being oppositely poled.

4. A relay as defined in claim 1 and further characterized by:

each said pair of contact surfaces including a pair of substantially coplanar surfaces with one said pair disposed in mirror-imaged relationship to said other pair.

5. A relay as defined in claim 4 and further characterized by:

said armature having a rotationally symmetrical configuration and movable in a linear path in switching between said pairs of contact surfaces.

6. A relay as defined in claim 5 and further characterized by:

said rotationally symmertical armature having an aperture passing therethrough concentrically of an axis of symmetry and parallel to said linear path of movement.

7. A relay as defined in claim 4 and further characterized by:

a pair of oppositely poled permanent magnets disposed outwardly of said means forming said switching space,

each said permanent magnet extending between different pairs of contact elements including one said contact elements forming one said contact surface, of different ones of said pairs of contact surfaces.

whereby, said pair of permanent magnets premagnetize said contact surfaces with substantially coplanar contact surfaces being oppositely poled.

'8. A relay as defined in claim 1 and further characterized by:

said means forming said switching space comprising an electrically and magnetically neutral material.

9. A relay as defined in claim 1 and further characterized by:

said electrically conductive fluid comprising mercury;

and

said means forming said sealed switching space comprising glass.

10. A relay as defined in claim 1 and further characterized by:

each said contact surface and said armature formed of magneticallyjconductive material; and

at least one said pair of contact surfaces being premagnetized and oppositely poled to retain said armature in bridging relationship therewith until said selectively operative armature moving means switches said armature to said other pair of contact surfaces.

11. A relay as defined in claim 1 and further characterized by:

said selectively operative armature moving means comprising an electrically conductive winding disposed about said means forming a sealed switching space in a manner to cause said armature to switch between said pairs of contact surfaces in response to passing a current pulse through said winding. 12. A relay as defined in claim 1 and further characterized by:

said armature moving in a linear path in switching between said pairs of contact surfaces. 13. A position-independent relay comprising: means forming a sealed switching space; means providing two pairs of contact elements electrically connectable exteriorly of said sealed switching space and forming two pairs of spaced apart, electrically conductive contact surfaces on portions of interior wall surfaces of said switching space,

two of said contact surfaces being formed substantially coplanar, another two said contact surfaces being canted inwardly of said switching space in a V-shaped configuration and projecting toward said coplanar contact surfaces, and each said pair of contact surfaces including diagonally opposite contact surfaces; means forming an electrically conductive armature disposed within said switching space for selective movement between said pairs of contact surfaces to provide an electrically conductive bridge between said contact surfaces of either of said pairs,

said armature including a sheet-form member having a V-shaped configuration in transverse cross section, and said V-shaped armature being sized and configured relative to saidswitching space to sweep an entire volume thereof in moving from bridging relationship with either of said pairs of contact surfaces into bridging relationship with said other pair of contact surfaces;

a supply of electrically conductive fluid contained within said switching space; and

selectively operative means for moving said armature from bridging relationship with either of said pairs of contact surfaces into lbridging relationship with said other pair of contact surfaces,

whereby, scattered droplets of said electrically conductive fluid are collected and forced between said armature and said one pair of contact surfaces ebing electrically bridged by said armature as the latter sweeps said switching space in moving between said pairs of contact surfaces to form said one pair of contact surfaces being electrically bridged contact surfaces.

14. A relay as defined in claim 13 and further characterized by:

a pair of identically polarized permanent magnets disposed outwardly of said means forming said switching space,

each said permanent magnet extending between dilferent pairs of contact elements including one said element forming one said canted surface and one said element forming one said coplanar surface.

whereby, said pair of permanent magnets premagnetize said contact surfaces with diagonally opposed contact surfaces being oppositely poled.

References Cited UNITED STATES PATENTS 2,844, 688 7/1958 Pfann 335--56 3,361,995 1/1968 Marcum 335-66 3,380,006 4/1968 Donath 335-56 BERNARD A. GILHEANY, Primary Examiner R. N. ENVALL, JR., Assistant Examiner US. Cl. X.R. 200-152; 335-153 

